The objectives of the project are: I. To pursue further the purification of the thyroid component homologous to LATS. II. To obtain further understanding of the mode of action of LATS in the thyroid. III. To establish a competitive protein-binding assay for LATS. IV. To try to measure variation in immune-competence throughout the course of Graves' disease, looking for changes coinciding with remission of relapse of hyperthyroidism. V. To test the possible role of emotion in the formation of LATS by experimental production of a thyroid-stimulating antibody in animals subjected to stressful stimuli, or so treated as to mimic a possible emotion-induced state of thyroid hyperfunction. VI. Largely explored in 1972-73, to test pituitary function in Graves' disease by both T3 suppression tests and by responsiveness to thyrotropin-releasing hormone, measuring both thyrotropin and prolactin in serum.